System and Method of Applying Material to a Surface

ABSTRACT

In accordance with example embodiments, a system may include a first feeder configured to transport asphalt, a second feeder configured to receive the asphalt from the first feeder, and a controller configured to control a speed of the first feeder and the second feeder in response to an input from an operator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/947,153 which was filed with the United States Patent andTrademark Office on Mar. 3, 2014, the entire contents of which areherein incorporated by reference.

BACKGROUND

1. Field

Example embodiments relate to systems and methods of applying amaterial, for example, asphalt, to a surface.

2. Description of the Related Art

FIG. 1A is a view of a system 5 used for applying asphalt to a road. Asshown in FIG. 1A, the system 5 includes a dump truck 10, a materialtransfer vehicle 50, and a paver 90. In the conventional art, thematerial transfer vehicle 50 includes a hopper 55, a first feeder 60, asecond feeder 65, and a third feeder 70. The hopper 55 is configured toreceive asphalt from the dump truck 10 and the first feeder 60 isconfigured to move the asphalt to the second feeder 65. The secondfeeder 65 includes an auger system to mix the asphalt and feed theasphalt to the third feeder 70 which, in turn, is configured to move theasphalt to the paver 90.

FIG. 1B is a partial schematic view of the material transfer vehicle 50.As shown in FIG. 1B, the material transfer vehicle 50 includes a firstelectronically controlled hydrostatic pump configured to drive a firsthydraulic drive motor which in turn is configured to drive the firstfeeder 60, a second electronically controlled hydrostatic pumpconfigured to drive a second hydraulic drive motor which in turn isconfigured to drive the second feeder 65, and a third electronicallycontrolled hydrostatic pump configured to drive a third hydraulic drivemotor which in turn is configured to drive the third feeder 70. In theconventional art the first feeder 60 may be controlled by a user inputwhereas the second and third feeders 65 and 70 receive a fixed signal sothat they operate at a relatively high speed.

In the system 5 of FIG. 1A the first feeder 60 includes a chain 72driven by a sprocket which is driven by a hydraulic motor. FIG. 2, forexample, is a partial view of the chain 72. The chain 72 resembles abelt with paddles and/or slats 75 used to move the asphalt 80 along thefirst feeder 60. Similarly, the third feeder 70 includes a chain whichalso resembles a belt with paddles and/or slats.

FIG. 3A is a view of another system 100 used for applying asphalt to aroad. As shown in FIG. 3A, the system 100 includes a dump truck 110, amaterial transfer vehicle 150, and a paver 190. In this conventionalsystem 100 the material transfer vehicle 150 includes a first hopper155, a first feeder 160, a second hopper 157, a second feeder 165, and athird feeder 170. The first hopper 155 is configured to receive asphaltfrom the dump truck 110 and the first feeder 160 is configured to movethe asphalt to the second hopper 157 where it is transferred, via thesecond feeder 165, to the third feeder 170. The third feeder 170, inturn, moves the asphalt to the paver 190. In this system 100, the first,second, and third feeders 160, 165, and 170 include chains driven byhydraulic motors. The chains, for example, resemble belts with paddlesand/or slats as was previously described.

FIG. 3B is a partial schematic view of the material transfer vehicle150. As shown in FIG. 3B, the material transfer vehicle 150 includes afirst electronically controlled hydrostatic pump configured to drive afirst hydraulic drive motor which in turn is configured to drive thefirst feeder 160, a second electronically controlled hydrostatic pumpconfigured to drive a second hydraulic drive motor which in turn isconfigured to drive the second feeder 165, and a third electronicallycontrolled hydrostatic pump configured to drive a third hydraulic drivemotor which in turn is configured to drive the third feeder 170. In theconventional the first and second feeders 160 and 165 are controlled byuser inputs and the third feeder 170 is configured to receive a fixedsignal which causes it to operate at a relatively high speed.

In each of the above described systems 5 and 100, hydraulic motors areused to control the operations of the first feeders 60 and 160, thesecond feeders 65 and 165, and the third feeders 70 and 170. In general,the first, second, and third feeders 60 and 160, 65 and 165, and 70 and170 are independently controlled. In normal operation, the second feeder65 and the third feeders 70 and 170 are set to deliver asphalt at arelatively high rate regardless of the setting of the first feeders 60and 160 or the second feeder 165. This manner of controlling the systems5 and 100 prevents asphalt delivered from the first feeders 60 and 160to the second feeders 65 and 165 (and then to the third feeders 70 and170) from over-accumulating in the material transfer vehicle.

SUMMARY

The inventor has noted that while conventional paving systems do anadequate job of applying asphalt to the ground, the conventional systemssuffer several drawbacks. First, because conventional systems generallyoperate certain feeders to deliver asphalt at a relatively high rate,the wear on these feeders is relatively high compared to the wear offeeders which may be operated at a lower rate. Second, because somefeeders are generally set to deliver asphalt at a fairly high rateregardless of material volume, the asphalt moved by these feeders maycause the asphalt to unnecessarily segregate. Third, the inventor notesconventional transfer vehicles lack indicators indicating the level ofasphalt that is present in the material transfer vehicles. As aconsequence, the only way to determine a level of asphalt in a materialtransfer vehicle is to manually inspect the material transfer vehiclestorage hopper from above. In view of the above problems, the inventorhas set out to improve conventional systems and/or methods of applyingasphalt to a surface. As a result, the inventor has developed a noveland nonobvious system and method of applying asphalt to surfaces. Theinvention, however, is not limited thereto, as the inventive conceptsrecited herein may be applied in other industries and technologies wherematerials are applied to surfaces. For example, the material may be, butis not limited to, concrete, sand, gravel, or some other material.

In accordance with example embodiments, a system may include a firstfeeder configured to transport asphalt, a second feeder configured toreceive the asphalt from the first feeder, and a controller configuredto control a speed of the first feeder and the second feeder in responseto a single input from an operator.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments are described in detail below with reference to theattached drawing figures, wherein:

FIGS. 1A and 1B are views of a system in accordance with theconventional art;

FIG. 2 is a partial view of a feeder in accordance with the conventionalart;

FIGS. 3A and 3B are views of another system in accordance with theconventional art;

FIG. 4 is a view of a system in accordance with example embodiments;

FIG. 5 is a view of a system in accordance with example embodiments;

FIG. 6A is a view of a system in accordance with example embodiments;

FIG. 6B is a view of a system in accordance with example embodiments;

FIG. 6C is a view of a system in accordance with example embodiments;

FIG. 6D is a view of a system in accordance with example embodiments;

FIG. 6E is a view of a system in accordance with example embodiments;

FIG. 7 is a view of a system in accordance with example embodiments;

FIG. 8 is a view of a system in accordance with example embodiments;

FIG. 9 is a view of a system in accordance with example embodiments;

FIG. 10 is a view of a system in accordance with example embodiments;

FIG. 11 is a partial view of a hopper with a level sensor and aproximity sensor in accordance with example embodiments;

FIG. 12 is a partial view of a hopper with a material inside inaccordance with example embodiments; and

FIG. 13 is a partial view of a hopper with a material inside inaccordance with example embodiments.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings, in which example embodiments of the inventionare shown. The invention may, however, be embodied in different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. In the drawings, the sizes ofcomponents may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itcan be directly on, connected to, or coupled to the other element orlayer or intervening elements or layers that may be present. Incontrast, when an element is referred to as being “directly on,”“directly connected to,” or “directly coupled to” another element orlayer, there are no intervening elements or layers present. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer, and/orsection from another elements, component, region, layer, and/or section.Thus, a first element component region, layer or section discussed belowcould be termed a second element, component, region, layer, or sectionwithout departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the structure in use or operation in addition to theorientation depicted in the figures. For example, if the structure inthe figures is turned over, elements described as “below” or “beneath”other elements or features would then be oriented “above” the otherelements or features. Thus, the exemplary term “below” can encompassboth an orientation of above and below. The structure may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein interpreted accordingly.

Embodiments described herein will refer to plan views and/orcross-sectional views by way of ideal schematic views. Accordingly, theviews may be modified depending on manufacturing technologies and/ortolerances. Therefore, example embodiments are not limited to thoseshown in the views, but include modifications in configurations formedon the basis of manufacturing process. Therefore, regions exemplified inthe figures have schematic properties and shapes of regions shown in thefigures exemplify specific shapes or regions of elements, and do notlimit example embodiments.

The subject matter of example embodiments, as disclosed herein, isdescribed with specificity to meet statutory requirements. However, thedescription itself is not intended to limit the scope of this patent.Rather, the inventors have contemplated that the claimed subject mattermight also be embodied in other ways, to include different features orcombinations of features similar to the ones described in this document,in conjunction with other technologies. Generally, example embodimentsrelate to systems and methods of applying a material, for example,asphalt, to a surface.

FIG. 4 is an example of a system having a first feeder 500 and a secondfeeder 600 in accordance with example embodiments. In exampleembodiments the first and second feeders 500 and 600 may be associatedwith a paving system and may be configured to move asphalt. For example,the first and second feeders 500 and 600 may be associated with amaterial transfer vehicle.

In example embodiments the first and second feeders 500 and 600 mayinclude chains that resemble belts with paddles as is well known in theart. For example, each of the first and second feeder systems 500 and600 may include a chain supported by a plurality of rollers wherein oneof the rollers is connected to a sprocket driven by a motor. In exampleembodiments, the first feeder 500 may be powered by a first motor andthe second feeder 600 may be powered by a second motor. In exampleembodiments, the first and second motors may be, but are not required tobe, hydraulic motors. For example, the first and second motors may beelectric motors.

In example embodiments the first feeder 500 may include a chain of afirst size and the second feeder 600 may include a chain of a secondsize. Thus, in example embodiments, the chains of the first and secondfeeder systems 500 and 600 may move different amounts of a material ifthey are operated at the same speed. For example, if the chain of thefirst feeder 500 has a width of four feet and the chain of the secondfeeder 600 has a width of two feet and both chains are operated at thesame speed, then the first chain may move twice an amount of materialwith respect to an amount of material moved by the second chain over asame time period. Of course, if the second chain were operated at aspeed which was twice the speed of the first chain then both chains maymove a same amount of material over a given time period.

In example embodiments the chains of the first and second feeders 500and 600 may be controlled simultaneously. As such, the first and secondfeeders 500 and 600 may be, but are not required to be, controlled sothat they deliver a same amount of material over a same time period. Forexample, in example embodiments, a first motor configured to operate thefirst feeder 500 and a second motor configured to operate the secondfeeder 600 may be simultaneously controlled by a controller which may beconfigured to receive input from an operator or some other source, forexample, a wireless transmitter or a sensor. In example embodiments thesensor may be configured to send a signal either directly or indirectlyto the controller. The controller, for example, may be configured tocontrol the first motor and the second motor based on the input from theoperator or from a signal sent by a sensor, such that an amount ofmaterial moved by the first and second feeders 500 and 600 over a sametime period may be the same despite differing belt sizes bysimultaneously reducing and/or minimizing the speed at which the firstand second motors operate. Furthermore, in example embodiments, each ofthe first and second feeders 500 and 600 may be controlled in accordancewith single input provided by the operator or the other source. Thoughexample embodiments illustrate a concept of controlling first and secondfeeders to move a same amount of material over a same time period,example embodiments are not limited thereto. For example, the secondfeeder may be controlled to move more material or less material than isbeing provided by the first feeder.

In example embodiments each of the first and second feeders 500 and 600may be simultaneously controlled and may be simultaneously controlled bya single input. Thus, in example embodiments, if an operator decides toreduce an amount of material moved by the first feeder 500 the operatormay input data to the controller to reduce a speed of the first motor.In example embodiments, the controller may further respond bycontrolling a speed at which the second motor operates to reduce a speedat which the second motor operates (thereby reducing a speed of thesecond feeder 600). This stands in stark contrast to conventionalfeeders of conventional paving systems wherein adjacent feeders arecontrolled independently of one another (or are not adjustable) andadjusting a speed of a first feeder does not change a speed of a secondfeeder.

In example embodiments the controller may be further configured toreceive operating parameters of the first and second feeders 500 and600. For example, in example embodiments the first and second feeders500 and 600 may include sensors which measure a parameter such as, butnot limited to, pressure, electrical current, or torque. For example, inthe event the first and second motors of the first and second feeders500 and 600 are hydraulic motors, the parameter may be associated with apressure of a fluid entering the hydraulic motor. On the other hand, ifthe first and second motors are electrical motors then the parameter maybe associated with electrical current flowing through the motors. As yetanother example, the parameter may be torque exerted by the first andsecond motors operating the first and second feeders 500 and 600. Bymeasuring the torque (or pressure or current) an overload on the systemmay be detected and the system may slow the first and second feeders 500and 600 down to minimize wear or it may control the first and secondmotors to prevent overloading. For example, the controller may be acomputer having a memory with a plurality of control parameters storedin a table. In example embodiments, the control parameters may, forexample, be related to pressure or current or torque. For example, iftorque exerted by the first motor exceeds a first value the controllermay be configured to reduce a speed of the first motor and the secondmotor to prevent the first motor from overloading while stillmaintaining a consistent material flow through the system. On the otherhand, if the torque is relatively low (for example, if no material isbeing moved) then the controller may shut off the first and secondmotors thereby conserving fuel and wear.

As indicated above, the controller of example embodiments may beconfigured to change speeds of the first feeder 500 and the secondfeeder 600. For example, in one example embodiment, the first and secondfeeders 500 and 600 may be controlled to operate at a first non-zerospeed. In this particular nonlimiting example embodiment, an operatormay provide a single input to the controller which either increases ordecreases speeds of the first and second feeders 500 and 600 to a secondnonzero speed. In the alternative, if the first and second feeders 500and 600 initially operate at different nonzero speeds, the controllermay (in response to the single input) change a speed of the first feeder500 to another nonzero speed and change the speed of the second feeder600 to another nonzero speed which may or may not be the same as thespeed of the first feeder 500. This latter embodiment may be especiallyapplicable in cases where the chains of the first and second feeders 500and 600 have a different size. Although the above description indicatesthat a single input may be used to change speeds of the first and secondfeeders 500 and 600, the invention is not limited thereto. For example,in example embodiments the controller may be configured to adjust speedsof the first and second feeders 500 and 600 based on input from sensorsassociated with the first and second feeders 500 and 600 or input fromsensors not directly associated with the first and second feeders 500and 600. For example, in this latter embodiment the second feeder 600may transport asphalt to a hopper of a paver. The hopper may include asensor indicating how much asphalt is residing therein. In this case,the sensor in the hopper may send a signal which may be utilized by thecontroller to control the speeds of first and second feeders 500 and600. For example, if the level of asphalt in the hopper is low thecontroller may increase the speeds of the first and second feeders 500and 600. If the level of asphalt in the hopper is high the controllermay increase the speeds of the first and second feeders 500 and 600.

FIG. 6A is a block diagram illustrating an implementation of theinventive concepts. In particular, FIG. 6A illustrates an example of asystem 2000 configured to apply a material to a surface. In exampleembodiments the system 2000 includes a controller 2100, a plurality ofelectronically controlled hydrostatic pumps 2200, a plurality ofhydraulic drive motors 2300, a plurality of feeders 2400, and an inputmodule 2500. In example embodiments the controller 2100 may be anelectronic controller, for example, a computer configured to control theplurality of hydrostatic pumps 2200. In example embodiments the system2000 may be embodied in a material transfer vehicle which may beconfigured to transfer a material, for example, asphalt.

In example embodiments the plurality of electronically controlledhydrostatic pumps 2200 is illustrated as being comprised of a firsthydrostatic pump 2200-1, a second hydrostatic pump 2200-2, and a thirdhydrostatic pump 2200-3. The number of hydrostatic pumps, however, isnot intended to limit the invention. For example, in example embodimentsthe plurality of electronically controlled hydrostatic pumps 2200 mayinclude only two hydrostatic pumps or more than three hydrostatic pumps.Similarly, plurality of hydraulic drive motors 2300 is illustrated asbeing comprised of three hydraulic motors, however, the plurality ofhydraulic drive motors 2300 may include only two hydraulic drive motorsor more than three hydraulic drive motors. Similar yet, the plurality offeeders 2400 is illustrated as being comprised of three feeders, howeverthe plurality of feeders 2400 may include only two feeders or more thanthree feeders.

In example embodiments the input device 2500 may be configured, but isnot required to be configured, to be controlled by an operator. Forexample, the input device 2500 may resemble a switch or a dial. Inexample embodiments the electronic controller 2100 may be configured tocontrol the plurality of feeders 2400 based on the input from the inputdevice 2500. For example, if an operator decides to increase the rate atwhich material is moved by the first feeder 2400-1 of the plurality offeeders 2400 the operator may use the input device 2500 to send a signalto the electronic controller 2100. In response, the electroniccontroller 2100 would control the first feeder 2400-1 by controlling thefirst electronically controlled hydrostatic pump 2200-1 and hydraulicdrive motor 2300-1 to increase the speed of the first feeder 2400-1.Simultaneously (or nearly simultaneously) the electronic controller 2100may also control the second and third feeders 2400-2 and 2400-3 toincrease their speeds by controlling the second and third electronicallycontrolled hydrostatic pumps 2200-2 and 2200-3 and the hydraulic motors2300-2 and 2300-3 to ensure material is controllably moved through thesystem 2000. Thus, in example embodiments, a single input may adjust thespeed of multiple feeders.

In addition to the input device 2500, the system 2000 may includevarious sensors that may be configured to measure various operationalparameters associated with the plurality of hydraulic drive motors 2300.These parameters may be uploaded to the electronic controller 2100 sothat the electronic controller 2100 may control the plurality of feeders2400 based on the sensed parameters. For example, FIG. 6C illustratesthe system 2000 which further includes pressure sensors 2500-1, 2500-2,and 2500-3. In example embodiments the pressure sensor 2500-1 may, forexample, sense a pressure of fluid between the first electronicallycontrolled hydrostatic pump 2200-1 and the first hydraulic drive motor2300-1, the pressure sensor 2500-2 may, for example, sense a pressure offluid between the second electronically controlled hydrostatic pump2200-2 and the second hydraulic drive motor 2300-2, and the pressuresensor 2500-3 may, for example, sense a pressure of fluid between thethird electronically controlled hydrostatic pump 2200-3 and the thirdhydraulic drive motor 2300-3. In example embodiments the pressuresensors 2500-1, 2500-2, and 2500-3 may communicate data to theelectronic controller 2100 either through wires or wirelessly and theelectronic controller 2100 may use this data to control the speeds ofthe first, second, and third feeders 2400-1, 2400-2, and 2400-3. Forexample, if a pressure sensed by any one of the three sensor 2500-1,2500-2, and 2500-3 is above or below a first preset or predeterminedvalue the electronic controller 2100 may simultaneously increase ordecrease the speed of the first, second, and third feeders 2400-1,2400-2, and 2400-3.

FIG. 6B is a block diagram of another system 2000′ in accordance withexample embodiments. In example embodiments the system 2000′ shares manyfeatures in common with the system 2000 of FIG. 6A. For example, inexample embodiments, the system 2000′ includes a controller 2100′, aplurality of electronically controlled hydrostatic pumps 2200′, aplurality of hydraulic drive motors 2300′, a plurality of feeders 2400′,and an input module 2500′. In example embodiments the controller 2100′may be an electronic controller, for example, a computer configured tocontrol at least some of hydrostatic pumps of the plurality ofhydrostatic pumps 2200′.

In example embodiments the plurality of electronically controlledhydrostatic pumps 2200′ is illustrated as being comprised of a firsthydrostatic pump 2200-1′, a second hydrostatic pump 2200-2′, and a thirdhydrostatic pump 2200-3′. The number of hydrostatic pumps, however, isnot intended to limit the invention. For example, in example embodimentsthe plurality of electronically controlled hydrostatic pumps 2200′ mayinclude only two hydrostatic pumps or more than three hydrostatic pumps.Similarly, the plurality of hydraulic drive motors 2300′ is illustratedas being comprised of three hydraulic motors, however, the plurality ofhydraulic drive motors 2300′ may include only two hydraulic drive motorsor more than three hydraulic drive motors. Similar yet, the plurality offeeders 2400′ is illustrated as being comprised of three feeders,however the plurality of feeders 2400′ may include only two feeders ormore than three feeders.

In example embodiments the input device 2500′ may be configured, but isnot required to be configured, to be controlled by an operator. Forexample, the input device 2500′ may resemble a switch or a dial. Inexample embodiments the electronic controller 2100′ may be configured tocontrol at least some of the feeders of the plurality of feeders 2400′based on the input from the input device 2500′. For example, if anoperator decides to increase the rate at which material is moved by thesecond feeder 2400-2′ and third feeder 2400-3′ of the plurality offeeders 2400′ the operator may use the input device 2500′ to send asignal to the electronic controller 2100′. In response, the electroniccontroller 2100′ may control the second and third feeders 2400-2′ and2400-3′ to increase their speeds by controlling the second and thirdelectronically controlled hydrostatic pumps 2200-2′ and 2200-3′ and thehydraulic motors 2300-2′ and 2300-3′ to ensure material is controllablymoved through the system 2000′.

In addition to the input device 2500′, the system 2000′ may includevarious sensors that may be configured to measure various operationalparameters, for example, a fluid pressure associated with the pluralityof hydraulic drive motors 2300′. These parameters may be uploaded to theelectronic controller 2100′ so that the electronic controller 2100′ maycontrol at least some of the feeders of the plurality of feeders 2400′based on the sensed parameters. For example, FIG. 6D illustrates thesystem 2000′ further including pressure sensors 2500-2′ and 2500-3′. Inexample embodiments the pressure sensor 2500-2′ may, for example, sensea pressure of fluid between the second electronically controlledhydrostatic pump 2200-2′ and the second hydraulic drive motor 2300-2′,and the pressure sensor 2500-3′ may, for example, sense a pressure offluid between the third electronically controlled hydrostatic pump2200-3′ and the third hydraulic drive motor 2300-3′. In exampleembodiments the pressure sensors 2500-2′ and 2500-3′ may communicatedata to the electronic controller 2100′ either through wires orwirelessly and the electronic controller 2100′ may use this data tocontrol the speeds of the second and third speeders 2400-2′ and 2400-3′.For example, if a pressure sensed by any one of the two sensors 2500-2′and 2500-3′ is above or below a first preset or predetermined value theelectronic controller 2100′ may simultaneously increase or decrease thespeed of the second and third feeders 2400-2′ and 2400-3′.

In example embodiments the system 2000′ is similar to the system 2000 inmany respects. However, in example embodiments the controller 2100 isconfigured to simultaneously control all of the feeders of the pluralityof feeders 2400 whereas the controller 2100′ is configured to providesimultaneous control of only a few of the feeders of the plurality offeeders 2400′. Thus, in the system 2000′, the speed of the first feeder2400-1 may be controlled independently from the speeds of the second andthird feeders 2400-2′ and 2400-3′. In example embodiments, this may beaccomplished by providing a separate input means 2501′ which may beconnected to a controller (not shown) which controls the firstelectronically controlled hydrostatic pump 2200-1′ and hydraulic motor2300-1′. This, however, is not meant to be a limiting feature of exampleembodiments. For example, rather than providing a separate input means2501′ and a separate controller the system 2000′ may use the inputmodule 2500′ to send a signal to the controller 2100′ which may beconfigured to operate the second and third feeders 2400-2′ and 2400-3′independently of the first feeder 2400-1′. In the alternative, theseparate input means 2501′ may send a signal, either wirelessly or overwires, to the electronic controller 2100′. In this embodiment theelectronic controller 2100′ may be further configured to control thefirst electronically controlled hydrostatic pump 2200-1′. As such, inthe embodiment of FIG. 6B, two user inputs may control the system 2000′.The first user input may be provided to the electronic controller 2100′to control a speed of the first feeder 2400-1′ and the second input maybe provided to the electronic controller 2100′ to simultaneously controlthe second and third feeders 2400-2′ and 2400-3′. It is understood inexample embodiments that although FIG. 6B illustrates two input means2500′ and 2501′ to provide input, the two input means 2500′ and 2501′may be integrated as a single device configured to send two user inputsto the electronic controller 2100′ and the electronic controller 2100′may be configured to control the first feeder 2400-1′ based on a firstuser input and control the feeders 2400-2′ and 2400-3′ simultaneouslybased on a second input.

FIG. 6E is a block diagram illustrating another implementation of theinventive concepts. In particular, FIG. 6E illustrates an example of asystem 2000″ configured to apply a material to a surface. In exampleembodiments the system 2000″ includes a controller 2100″, a plurality ofelectronically controlled hydrostatic pumps 2200″, a plurality ofhydraulic drive motors 2300″, a plurality of feeders 2400″, and an inputmodule 2500″. In example embodiments the controller 2100″ may be anelectronic controller, for example, a computer configured to control atleast some of the plurality of hydrostatic pumps 2200″. For example, inFIG. 6E the electronic controller 2100″ is illustrated as beingconfigured to control two of the three illustrated electronicallycontrolled hydrostatic pumps. In example embodiments the system 2000″may be embodied in a material transfer vehicle which may be configuredto transfer a material, for example, asphalt.

In example embodiments the plurality of electronically controlledhydrostatic pumps 2200″ is illustrated as being comprised of a firsthydrostatic pump 2200-1″, a second hydrostatic pump 2200-2″, and a thirdhydrostatic pump 2200-3″. The number of hydrostatic pumps, however, isnot intended to limit the invention. For example, in example embodimentsthe plurality of electronically controlled hydrostatic pumps 2200″ mayinclude only two hydrostatic pumps or more than three hydrostatic pumps.Similarly, plurality of hydraulic drive motors 2300″ is illustrated asbeing comprised of three hydraulic motors, however, the plurality ofhydraulic drive motors 2300″ may include only two hydraulic drive motorsor more than three hydraulic drive motors. Similar yet, the plurality offeeders 2400″ is illustrated as being comprised of three feeders(2400-1″, 2400-2″, and 2400-3″), however the plurality of feeders 2400″may include only two feeders or more than three feeders.

In example embodiments the input device 2500″ may be configured, but isnot required to be configured, to be controlled by an operator. Inaddition (or in the alternative) the electronic controller 2100″ may beconfigured to receive input from a sensor 2600″ which may sense aparameter associated with one of the elements of the system 2000″. Forexample, as shown in FIG. 6E, the sensor 2600″ is shown as beingpositioned to sense a parameter associated with the first feeder2400-1″. For example, the sensor 2600″ may be configured to sense howfast a chain of the first feeder 2400-1″ is being operated and may senddata related to the speed of the chain back to the electronic controller2100″ which may use this data to control the second and/or third feeders2400-2″ and 2400-3″.

In example embodiments the sensor 2600″ is shown as being configured tosense a parameter associated with the first feeder 2400-1″, however,this is not intended to limit example embodiments. For example, ratherthan positioning the sensor 2600″ to detect a parameter of the firstfeeder 2400-1″, the sensor 2600″ may be configured to sense a parameterassociated with another component of the system 2000″, for example,pressure associated with the first hydraulic drive motor 2300-1″. Inthis latter embodiment the controller 2100″ may use this sensedparameter to control the second and/or third feeders 2400-2 and 2400-3.Examples of the sensor 2600″ may be, but are not required to be, a flowmeters, sonic sensors, and amperage sensing devices.

In example embodiments the system 2000″ may further include a user input2500″ to provide communication between a user and the electroniccontroller 2100″. For example, the input device 2500″ may resemble aswitch or a dial. In example embodiments the electronic controller 2100″may be configured to control the plurality of feeders 2400 based on theinput from the input device 2500″. For example, if an operator decidesto increase the rate at which material is moved by the second feeder2400-2″ and the third feeder 2400-3″ of the plurality of feeders 2400″the operator may use the input device 2500″ to send a signal to theelectronic controller 2100″. In response, the electronic controller2100″ would control the second feeder 2400-2″ and the third feeder2400-3″ by controlling the second electronically controlled hydrostaticpump 2200-2″ and the third hydrostatic pump 2200-3″ to increase thespeed of the second and third feeders 2400-2″ and 2400-3″.

In example embodiments, the system 2000″ may further include a seconduser input 2501″. Like the first user input 2500″, the second user input2501″ may be, but is not required to be, a switch or a dial. In thenonlimiting example of FIG. 6E the second user input 2501″ may be usedto control the first electronically controlled hydrostatic pump 2200-1″which thereby controls the first hydraulic drive motor 2300-1″ and thefirst feeder 2400-1″. In example embodiments the electronic controller2100″ may be configured to control the second and third feeders 2400-1″and 2400-3″ based on a parameter sensed by the sensor 2600″. Forexample, if a user controls the first feeder 2400-1″ via the second userinput 2501″ the electronic controller 2100″ may control the second andthird feeders 2400-1″ and 2400-3″ based on information sensed by thesensor 2600″. In this manner, a user may directly control a speed of thefirst feeder 2400-1″ and indirectly control the speeds of the second andthird feeders 2400-2″ and 2400-3″ via the controller 2100″ whichreceives input from the sensor 2600″.

In example embodiments the electronic controllers 2100, 2100′, and 2100″may be further configured to receive a signal and control the pluralityof feeders 2400, 2400′, and 2400″ based on the signal. For example, inexample embodiments the systems 2000, 2000′, and 2000″ may be embodiedin a material transfer vehicle configured to transport asphalt to ahopper of a paver. In example embodiments, the hopper of the paver mayinclude a sensor to detect an amount of asphalt in the hopper. Inexample embodiments the sensor may send a signal to the electroniccontrollers 2100, 2100′, and 2100″ either directly, or indirectly, andthe electronic controllers 2100, 2100′, and 2100″ may control theplurality of feeders 2400, 2400′, and 2400″ based on the signal. Forexample, if the signal sent by the sensor in the hopper indicated thelevel of asphalt therein was too high the electronic controllers 2100,2100′, and 2100″ may slow the speeds of the plurality of feeders 2400,2400′, and 2400″. Conversely, if the signal sent by the sensor in thehopper indicated the level of asphalt therein was too low the electroniccontrollers 2100, 2100′, and 2100″ may increase the speeds of theplurality of feeders 2400, 2400′, and 2400″.

FIG. 7 is a view of a paving system 5000 which implements the system2000 of FIG. 6A and or 6C. As shown in FIG. 7, the paving system 5000may include a dump truck 5100, a material transfer vehicle 5200, and apaver 5300. The material transfer vehicle 5200 may be substantiallyidentical to a material transfer vehicle marketed under Weiler E1250Awhich has been available since 2007. In example embodiments, thematerial transfer vehicle 5200 may include a hopper 5255, the firstfeeder 2400-1, the second feeder 2400-2, and the third feeder 2400-3.The hopper 5255 may be configured to receive asphalt from the dump truck5100 and the first feeder 2400-1 may be configured to move the asphaltto the second feeder 2400-2. The second feeder 2400-2 may include anauger system to mix the asphalt and feed the asphalt to the third feeder2400-3 which, in turn, is configured to move the asphalt to the paver5300. As such, the system 5000 of example embodiments is similar to theconventional art illustrated in FIGS. 1A and 1B, however, unlike theconventional art, the system 5000 further includes the controller 2100which may be configured to control the first electronically controlledhydrostatic pump 2200-1 and the first hydraulic motor 2300-1 whichcontrols the first feeder 2400-1. Similarly, the controller 2100 mayalso be configured to control the second electronically controlledhydrostatic pump 2200-2 and the second hydraulic motor 2300-2 whichcontrols the second feeder 2400-2. Similar yet, the controller 2100 mayalso be configured to control the third electronically controlledhydrostatic pump 2200-3 and the third hydraulic motor 2300-3 whichcontrols the third feeder 2400-3. In this particular example, anoperator may use the input device 2500 (which may be a single inputdevice) to control a speed of the first feeder 2400-1 to increase ordecrease the speed at which the first feeder 2400-1 operates. When thespeed of the first feeder 2400-1 is either increased or decreased thecontroller 2100 automatically controls the second and third feeders2400-2 and 2400-3 to increase or decrease their speeds as well. As such,the system 5000 is controlled such that asphalt (or another material)may move through the system 5000 in a controlled manner. Furthermore,the system is controlled such that a single input allows forsimultaneous control of three feeders. Further yet the system 5000 maybe configured so that the first feeder 2400-1, the second feeder 2400-2,and the third feeder 2400-3 are controlled so as to move a same amountof material despite having different belt sizes and/or differentvolumetric potential.

FIG. 8 is a view of another paving system 6000 which implements thesystem 2000′ of FIG. 6B and/or 6D. As shown in FIG. 8, the paving system6000 may include a dump truck 6100, a material transfer vehicle 6200,and a paver 6300. The material transfer vehicle 6200 may besubstantially identical to a material transfer vehicle marketed underWeiler E2850 which has been available since 2010. In exampleembodiments, the material transfer vehicle 6200 may include a hopper6255, the first feeder 2400-1′, the second feeder 2400-2′, and the thirdfeeder 2400-3′. The hopper 6255 may be configured to receive asphaltfrom the dump truck 6100 and the first feeder 2400-1′ may be configuredto move the asphalt to the second hopper 6257. The second feeder 2400-2′may be configured to receive the asphalt from the second hopper 6257 andmove the asphalt to the third feeder 2400-3′ which, in turn, may beconfigured to move the asphalt to the paver 6300. As such, the system6000 of example embodiments is similar to the conventional artillustrated in FIGS. 3A and 3B, however, unlike the conventional art,the system 6000 further includes the controller 2100′ which may beconfigured to control the second electronically controlled hydrostaticpump 2200-2′ and the second hydraulic motor 2300-2′ which controls thesecond feeder 2400-2′. Similar yet, the controller 2100′ may also beconfigured to control the third electronically controlled hydrostaticpump 2200-3′ and the third hydraulic motor 2300-3′ which controls thethird feeder 2400-3′. In this particular example, an operator may usethe input device 2500′ to simultaneously control a speed of the secondand third feeders 2400-2′ and 2400-3′ using a single input to increaseor decrease their speeds to ensure a consistent flow of material. Inthis latter embodiment, the speed of the first feeder 2400-1′ may beadjusted without having to adjust the speeds of the second and thirdfeeders 2400-2′ and 2400-3′. As such, the system 6000 is controlled suchthat asphalt (or another material) may move through the system 6000 in acontrolled manner.

In example embodiments, the controllers 2100 and 2100′ may be computerswith software loaded thereon to enable control of their associatedfeeders. This software may have algorithms embedded therein whichprevent a user from controlling various feeder speeds. For example, insome situations, for example, when the systems 2000 and 2000′ areinitially activated at a job site, the feeders 2400 and 2400′ may berelatively cold. If the feeders 2400 and 2400′ were operated at a slowrate when the feeders 2400 and 2400′ are cold the asphalt may cool tooquickly and cause some of the feeders 2400 and 2400′ to clog up. Inorder to prevent this from happening, the controllers 2100 and 2100′ mayhave algorithms built therein which cause certain feeders (for example,feeders 2400-2, 2400-3, and 2400-3′) to operate at a fairly high speedfor a certain time period, for example, fifteen minutes after start up,in order to ensure the feeders 2400 and 2400′ are sufficiently warmedfor efficient material transfer after which time the feeders 2400 and2400′ may be controlled via user input. In other words, the system mayhave set parameters and when the parameters are met, the system willactivate and allow operators to have full control of the variable speedfeeder system.

In accordance with example embodiments, a material transfer vehicle maycontain two or more independently driven conveyor, chain, auger, belt,or feeder systems in series and the speeds of independently drivenfeeder systems may be adjusted simultaneously with one or more speedadjustment inputs. This stands in stark contrast to the conventional artwherein speeds of individual feeder systems in a series of feeders on amaterial transfer vehicle were adjusted independently or are notadjustable. Thus, in the systems according to example embodiments excessfeeder system wear, excess fuel consumption, and an overallinefficiencies may be reduced. In example embodiments, speed/feed rateadjustment of multiple systems with one input may allow a machine tooperate more efficiently without additional operator requirements. Inaddition, reducing the feeder chain speeds may allow asphalt to movethrough the machine feeder system slower with less material segregation.This may allow better maintenance of temperature of the materialthroughout the machine which in turn may also reduce segregation.

In example embodiments, a material transfer vehicle may be equipped withload (pressure, current, torque) monitoring equipment on the feedersystem and/or the material transfer vehicle may be further equipped witha controller to control an engine or may vary the RPM of theindependently driven feeders. By monitoring the load on the feedersystem and/or engine it may be possible to increase or decrease feederspeed automatically in order to prevent machine stalling and excess fuelconsumption. If a particular system on the machine becomes over-loaded,the controls system may slow down the feeders automatically in order todecrease load. As soon as the overloading condition subsides the systemmay increase the speed of the feeders automatically to return it to anormal use. This may increase efficient use of machine power whilemaximizing the machines loading capabilities. In example embodiments aspeed of at least one of the feeders may be adjusted by changing theelectrical current to the control solenoid on the variable displacementhydraulic pump or by decreasing engine speed or a combination there of.

FIG. 9 is a view of a material transfer vehicle 9000 in accordance withexample embodiments. In FIG. 9, the material transfer vehicle 9000 isequipped with a sensor 9100 and a material level indicator 9200 whichindicates a level of the material (for example, asphalt) that may be ina hopper of the material transfer vehicle 9000. In example embodiments,the sensor 9100 may be, but is not required to be, an ultrasonic sensor.However, many other kinds of sensors may be employed which are wellknown in the art. For example, the inventive concepts of thisapplication include a use of a mechanical level gage to determine alevel of material in the hopper. In example embodiments, the materiallevel indicator 9200 may be coupled to the sensor 9100 such that a levelof the material detected by the sensor 9100 may be displayed by thematerial level indicator 9200. In this particular nonlimiting example,the material level indicator 9200 includes three lights stacked on topof each other. When the level of the material detected is low only thebottom most light may be activated. When a level of asphalt detectedindicates the hopper is approximately half full, the bottom two lightsmay be activated. When the hopper which is holding the asphalt is fullall three lights may be turned on.

In example embodiments, the sensor 9100 may be configured to wirelesslytransmit a signal to the electronic controller 2100. For example, inexample embodiments, if the hopper of the transfer device 9000 isdetected as being full, the controller may be configured to shut off thefirst feeder to prevent further asphalt from being loaded into thematerial transfer vehicle 9000. Example embodiments, however, are notlimited to systems which include wireless transmission of data. Forexample, rather than transmitting data wirelessly, data may becommunicated over a wire which may be installed on the equipment.

In addition to the above, example embodiments also allow for a systemthat uses the sensed data to determine an amount of weight of asphaltthat is stored in the material transfer vehicle 9000. In this particularnonlimiting example, the sensor may send data to the controller 2100which may be configured to use the sensed data to determine a weight ofthe material in the material transfer vehicle 9000. In exampleembodiments, the controller 2100 may be configured to shut down thefirst feeder in the event a weight limit associated with the materialtransfer vehicle 9000 is exceeded (or nearly exceeded) to prevent thematerial transfer vehicle 9000 from being overloaded with asphalt.

In example embodiments, the sensor 9100 may be used to determine theamount of asphalt inside of the main asphalt storage hopper on amaterial transfer vehicle 9000. The signal from the sensor 9100 may beconverted to an output which is displayed as visible lights external tothe machine. These indicator lights may act as a gauge that allows theoperator and other workers around the machine to see a full range (emptyto full) of material inside the storage hopper. This may also helpprevent a material transfer vehicle from accepting too much material.For example, Applicant notes that many conventional sites have weightand/or ground pressure limitations. Thus, by determining how muchasphalt is contained in a hopper of a material transfer vehicle, theinventive systems allow for a more accurate determination of vehicleweight, when loaded, to avoid exceeding the aforementioned limitations.This may also be accomplished by incorporating various load cells orsensors in the material transfer vehicle in order to measure how muchmaterial is in the hopper of the material transfer vehicle.

Previously, an operator on an operator platform 9300 was the onlyindividual on the jobsite that would be able to monitor the amount ofmaterial inside the storage hopper. The only way the operator would knowthe level of material was to uncover the hopper and physically lookinside. The level indicator lights allow the storage hopper level to beviewed in any condition (night or day) by anyone on the jobsite whileleaving the hopper fully sealed. With the hopper sealed the asphalttemperature is maintained and steam/fumes are kept away from theoperator.

Example embodiments provide several advantages over the prior art. Forexample, in example embodiments material height may be visible to anentire crew and/or other machine operators that may be on a groundlevel, heat retention of asphalt may be conserved, steam/fumes may beretained leading to increased job efficiency.

Also, as explained above, by sensing the level of material inside of thestorage hopper, another option would be to convert the level of materialinto a weight unit. Weight of the material transfer vehicle is vital onmany jobsites to prevent damage to the surface that the machine isdriving on. Through the use of weight monitoring and feeder control themaximum weight of material that is contained inside the storage hoppermay be controlled. If a maximum weight limit is set, a feeder that isfilling the storage hopper when the limit is met may be shut off.

In addition, the control systems of example embodiments may greatlyimprove management and planning. Normally when asphalt is applied to aroad it is done so with a fleet of dump trucks which bring asphalt tothe material transfer vehicles. In example embodiments, the speed of thefeeders of the material transfer vehicles may be adjusted to bettermatch the rate at which the dump trucks are bringing asphalt to thematerial transfer vehicles. For example, if the rate at which the dumptrucks are bringing asphalt to the material transfer vehicles isrelatively low, an operator of the material transfer vehicles maysimultaneously slow down at least some of the feeders to prevent theirwear and tear and conserve fuel.

Also, an important aspect of many jobs is a requirement that the levelmaterial in the hopper cannot be below a certain percentage from full;this is to prevent asphalt segregation. Through the use of thelevel/weight monitoring a level minimum may be set that would not allowmaterial within the hopper to drop below a set parameter. In addition,if the system is running without material (load) for a certain amount oftime the feeders may be turned off without operator input to preventexcess wear on components.

FIG. 10 is a view of a system 10000 in accordance with exampleembodiments. In example embodiments, the system 10000 may include afirst feeder 10160 configured to move a material, for example, asphalt,to a hopper 10157, and a second feeder configured to move the asphalt toa third feeder 10170 which may transfer the asphalt to a paver. Inexample embodiments, the system 10000 may resemble the Weiler E2850material transfer vehicle modified as described above so that a singleinput may modify speeds of more than one feeder. However, the system10000 may further include devices to quantify how much material may bepresent in the hopper 10157. The devices, for example, may include adistance sensor 10100 (for example, an ultrasonic sensor) and aninclination sensor 10200.

FIG. 11 is a cross section view of the hopper being filled with thematerial over time. For example, L1 indicates a material level in thehopper 10157 at a first time, L2 indicates a material level in thehopper 10157 at a later time and L3 indicates a material level in thehopper 10157 at yet a later time. As such, FIG. 11 illustrates thehopper being filled with a material over a time period. In FIG. 11 thedistance sensor 10100 is arranged to detect the material. As such, thedistance sensor 10100 may provide data indicating how full the hopper10157 is. When the distance sensor 10100 detects that the material isrelatively close to the sensor 10100 this information may infer thehopper 10157 is relatively full.

Applicant has discovered that while the distance information from thedistance sensor 10100 may be relatively valuable in and of itself, thatthe distance information alone may not be an accurate predictor as tohow full a hopper 10157 is. For example, if the system 10100 is inclinedin a first direction the material filling the hopper 10157 may not havethe substantially symmetric pattern illustrated in FIG. 11, rather, itmight have an asymmetric pattern as shown in FIG. 12. Furthermore, ifthe system 10000 were inclined in a second direction, the materialfilling the hopper 10157 may have a different asymmetric pattern asshown in FIG. 13. In fact, the degree of asymmetry may be dependent onthe amount the system 10000 is inclined. Thus, the information from thedistance sensor 10100 alone may not provide an accurate picture as tohow much material is in the hopper 10157.

To compensate for inclination, example embodiments may additionallyinclude the inclination sensor 10200. The inclination sensor 10200 maymeasure not only a front to back inclination of the system 10000, but aleft-to-right inclination as well. Furthermore, placement of theinclination sensor 10200 may be variable. For example, in oneembodiment, the inclination sensor 10200 may be placed in theenvironment of the hopper 10157 and next to the distance sensor 10100.In another embodiment, the inclination sensor 10200 may be placed out ofor away from the hopper 10157 in a controlled area, such as a frame thatmay be associated with the system 10000. Thus, the inclination sensor10200 may be placed in an area away from the hopper 10157 and thus notbe exposed to heat, debris, and other harmful elements that may bepresent in the hopper 10157. When the data from the inclination sensor10200 is combined with the data from the distance sensor 10100, thecombination of data may present a more accurate picture as to how fullthe hopper 10157 is compared to a system which only includes a distancesensor 10100. Also, although the embodiments thus far have describedonly a single distance sensor 10100 and a single inclination sensor10200, example embodiments may also include systems with multipledistance sensors 10100 and multiple inclination sensors 10200.

Example embodiments of the invention have been described in anillustrative manner. It is to be understood that the terminology thathas been used is intended to be in the nature of words of descriptionrather than of limitation. Many modifications and variations of exampleembodiments are possible in light of the above teachings. Therefore,within the scope of the appended claims, the present invention may bepracticed otherwise than as specifically described.

What we claim is:
 1. A system comprising: a first feeder configured totransport asphalt; a second feeder configured to receive the asphaltfrom the first feeder; and a controller configured to control a speed ofthe first feeder and the second feeder in response to at least one of aninput from an operator and a sensor.
 2. The system of claim 1, whereinthe first feeder includes a first motor and the second feeder includes asecond motor and the controller is configured to control the first andsecond motors.
 3. The system of claim 2, wherein the first motor is ahydraulic motor and the second motor is a hydraulic motor.
 4. The systemof claim 3, wherein the first motor is controlled by first hydrostaticpump and the second motor is controlled by a second hydrostatic pump andthe controller controls the first and second hydrostatic pumps tocontrol the first and second hydraulic motors.
 5. The system of claim 1,wherein the controller is configured to substantially simultaneouslyincrease and decrease speeds of the first and second feeders based onthe input from the operator.
 6. The system of claim 1, furthercomprising: a third feeder configured to receive the asphalt from thesecond feeder, wherein the controller is further configured to control aspeed of the third feeder in response to the input from the operator. 7.The system of claim 1, further comprising: a third feeder configured toprovide the asphalt to the second feeder, wherein the third feeder iscontrolled independently of the first and second feeders.
 8. The systemof claim 1, further comprising: a first load sensor configured tomeasure a first load associated with the first feeder; and a second loadsensor configured to measure a second load associated with the secondfeeder, wherein the controller is further configured to control a speedof the first and second feeders based on at least one of the first andsecond loads.
 9. The system of claim 8, wherein the first feederincludes a first motor and the second feeder includes a second motor andthe first load is a first pressure and the second load is a secondpressure.
 10. The system of claim 9, wherein the first and second motorsare hydraulic motors.
 11. A method comprising: moving asphalt with afirst feeder; moving the asphalt with a second feeder, the second feederreceiving the asphalt from the first feeder; and controlling speeds ofthe first feeder and the second feeder by inputting an input to acontroller.
 12. The method of claim 11, wherein the first feederincludes a first motor and the second feeder includes a second motor andcontrolling speeds of the first and second feeders includes controllingspeeds of the first and second motors.
 13. The method of claim 12,wherein the first motor is a hydraulic motor and the second motor is ahydraulic motor.
 14. The method of claim 13, wherein the first motor iscontrolled by first hydrostatic pump and the second motor is controlledby a second hydrostatic pump and controlling speeds of the first andsecond motors includes controlling speeds of the first and secondhydrostatic pumps.
 15. The method of claim 11, wherein controllingspeeds of the first and second feeders includes one of substantiallysimultaneously increasing and decreasing speeds of the first and secondfeeders.
 16. The method of claim 11, further comprising: moving theasphalt with a third feeder, wherein the controller is furtherconfigured to control a speed of the third feeder in response to theinput from the operator.
 17. The system of claim 11, further comprising:moving the asphalt via a third feeder to the second feeder, wherein thethird feeder is controlled independently of the first and secondfeeders.
 18. The method of claim 11, further comprising: controllingspeeds of the first and second feeders based on at least one of a firstload sensed by a sensor configured to measure a load associated with thefirst feeder and a second load sensor configured to measure a loadassociated with the second feeder.
 19. The method of claim 11, whereinthe first feeder includes a first motor and the second feeder includes asecond motor and the first load is a first pressure and the second loadis a second pressure.
 20. The system of claim 19, wherein the first andsecond motors are hydraulic motors.